Shepherd by Piers Anthony

scrotum. The pheromones formed a dense cloud. His member, well worn from the breeding cycle, surged into rigidity, filling Elen's channel. It wanted to burst through her and reach a vamp so it could be endlessly potent.
    He kept pedaling, and the boat kept moving.
    The vamps started kissing him everywhere they could reach, especially his scrotum and anus. Each kiss excited another section of his flesh.
    He pedaled.
    The urgency continued to build. When he feared it would overwhelm him and make him wrench free of Elen's closure, he lifted his head and started singing. “He who is noble...”
    “Excrement!” Lova swore. “The beast remembered!”
    Elen joined him. “...pure and simple hearted.”
    The vamps definitely were not that. They retreated, hurling vile expletives. They were furious, but could not handle the stirring music, or the spirit it evoked.
    They made it across and landed at the proper site. The sheep walked off the boat, followed by Vulture and Python. Only then did Shep and Elen disembark, still closely connected as he carried her. Once they were safely on land, beyond the reach of the vamps, they were ready to separate.
    “Unless you wish to complete it now,” Elen murmured.
    The pheromones still surrounded them. “Actually I do, to make up for all the prior frustration. Do you mind?”
    She squeezed him, just so, and he jetted powerfully into her. That established her dominance over the vampires, because now he was able to climax instead of remaining rigid while his blood was sucked.
    There was a chorus of expletives from the vamps still hovering over the water. His climax was his parting shot, leaving them angrily frustrated.
    The sheep had waited patiently while Shep and Elen finished their business. Then the sheep walked beside the lake, avoiding the way the party had come. About a quarter of the way around they struck out across a barren landscape. It might once have been a grass field, but now it was desiccated stubble.
    Vulture flew up, circled, and returned to earth, troubled. Shep saw smoke ahead, and smelled burning. “Uh-oh. I think we have a grass fire. We don't want to get caught in that.” Python seemed nervous too.
    But the sheep were marching right toward it, unconcerned.
    “Trust the sheep,” Elen said.
    “Of course. But sometimes I wish they could speak our language, and tell us what's coming.”
    “They communicate well enough. They don't need our kind of speech.”
    The fire loomed closer, being blown directly toward them. Gusts of wind brought the smoke down to swirl around them, making them cough.
    Python slithered rapidly ahead. Vulture followed, half flying. There was something.
    Then they saw it: the opening of a cave. Shelter from the fire! Provided it didn't harbor some predator waiting for prey to be driven into its lair. But of course the sheep would not blithely walk into that.
    It turned out to be a series of caves, linked by tunnel-like apertures as if a river had once coursed through it. Now it was bone dry. The sheep formed a file and walked on into it, leaving the light of day behind.
    “Trust the sheep,” Shep echoed. They followed closely after the last ewe, and Python and Vulture brought up the rear. The sounds of the sheep's hooves told them where to go.
    An hour later they emerged from the caves and found a completely different landscape. Green grass bordered a slow stream, and there were a few fruiting trees. It was a comparative paradise, a fine place to spend the night.
    The sheep had known.
    That night Shep and Elen clasped each other in the holddown mode, kissing and making love without sexual completion. It seemed natural.
    In the morning they were ready to resume travel, but the sheep were not. So they waited. Sure enough, a ferocious storm crossed suddenly over them, deluging them with water and raising the level of the river close to overflowing its banks. But in another hour the torrent cleared and they were able to resume walking.
    The rest of